Final answer:
The sentence is in the subjunctive mood, used for wishes, suggestions, or commands, as indicated by the base form 'take' following the verb 'recommend'.
Step-by-step explanation:
The sentence "I recommend that Richard take a math class before summer." is an example of the subjunctive mood. The subjunctive mood is used to express wishes, suggestions, or commands, and it often follows specific verbs or expressions, such as recommend, insist, request, and advise. In this case, the use of subjunctive is indicated by the use of the base form of the verb take after the word recommend, even though the subject is singular.